تابع ‎is_bool()‎‎ در PHP

<?php
$a = 1;
echo "a is " . is_bool($a) . "<br>";

$b = 0;
echo "b is  " . is_bool($b) . "<br>";

$c =  true;
echo "c is " . is_bool($c) .  "<br>";

$d = false;
echo "d is " . is_bool($d) . "<br>";
?>
<?php
$a = 1;
echo "a is " . is_bool($a) . "<br>";

$b = 0;
echo "b is  " . is_bool($b) . "<br>";

$c =  true;
echo "c is " . is_bool($c) .  "<br>";

$d = false;
echo "d is " . is_bool($d) . "<br>";
?>اجرای کد